I'm so glad this thread and forum exists.
I thought I was the only one noticing this.
I just took delivery of a 2017 100D and traded in my early 2013 85 which had the UHF system. I noticed a HUGE downgrade in audio quality in the new 100D.
It does have the premium upgrades/audio package.
What it sounds like is happening to me, regardless of EQ settings and issues, is that Tesla may be lowering the streaming bitrate from Slacker Radio?
The quality used to be flawless when streaming music, but I'm just guessing this is going on, especially because when I took delivery and asked about the new "subscription" you have to pay for to have internet and data service on the cars, the Service Center said "Yeah, our data bill is insanely high, we have to find a way to cut costs"...
I know on apps Pandora and Slacker Radio on a mobile phone the default is "low or normal quality" and you have to select "high quality" for something closer to a 320kbps.
Maybe we are all listening to streaming at 128kbps now and we used to have access to higher?
Also, a new and silly feature I've noticed on this car is every 5-6 songs you get an "ABC News Update" that turns on. Luckily you can skip it.